This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Introduction: How do people learn who to like? Behavioral observation provides one important source of information. Often, people make enduring positive and negative judgments of others based on limited observation. Little is known, though, about how the brain builds positive or negative social impressions on the basis of observation. Specific Aims: We aimed to determine whether increasing positive or negative impressions of another influenced activation in specific brain areas connected to reward and to thinking about others. Methods and Materials: We scanned participants with event-related FMRI in a novel social prediction task in which participants observed the outcomes of an earlier six-person repeated public goods game and made predictions about how much was donated on each round. Participants were not told in advance that the donation profiles of each player in the game were designed to be more or less altruistic.